Electric circuit breaker



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July 23, 1957 SCHEUERMEYER 2,800,558

ELECTRIC CIRCUIT BREAKER Filed May '7, 1956 2 Sheets Sheet 1 lnve n tor:Emil Scheuermeger,

July 23, 1957 SCHEUERMEYER I 2,800,558

ELECTRIC CIRCUIT BREAKER I 2 Sheets-Sheet 2 Filed May '7, 1-956Inventor: Emil Scheuerrneger,

United States Patent O ELECTRIC CIRCUIT BREAKER Emil Scheuermeyer,Drexel Hill, Pa., assignor to General Electric Company, a corporation ofl ew York Application May 7, 1956, Serial No. 583,126

14 Claims. (Cl. 200-146) This invention relates to an electric circuitbreaker or switch and, more particularly, to improvements in circuitbreakers or switches of the general type shown and claimed in U. S.Patent No. 2,399,485, issued to W. G. Harlow et al., and assigned to theassignee of the present application.

The circuit breaker of the aforementioned Harlow patent comprises amovable main contact and an arcing contact pivotally mounted on the maincontact. A suitably controlled spring causes the arcing contact to openat high speed after a predetermined opening movement of theslower-moving main contact, and this high speed motion of the arcingcontact desirably tends to minimize the duration of the arcing intervalduring an opening operation. During a closing operation, however, thearcing contact of the aforementioned Harlow patent moves at essentiallythe same speed as the main contact, and this has led to undesirably longarcing intervals as the contacts approach closed position, especiallywhere relatively slow speed closing devices are to be relied upon.

Accordingly, one of the objects of my invention is to effect high speedclosing movement of an arcing contact which is mounted on a relativelyslow-moving main contact.

Another object is to effect such high speed closing movement of anarcing contact by means of a new and improved stored-energy mechanismwhich lends itself to being readily included in a circuit breaker of thegeneral type shown in the aforementioned Harlow patent.

Another object is to design the stored-energy mechanism in such a manneras to preclude the possibility of objectionable contact-reboundfollowing a closing operation.

In carrying out my invention in accordance with one form thereof, Iprovide first contact structure, a main contact blade pivotally-mountedfor movement into and out of engagement with said first contactstructure, and an arcing contact pivotally mounted on said blade formovement with respect to both said blade and said first contactstructure. Closing movement of the arcing contact is controlled by achargeable spring having a pivotally-mounted lever coupled thereto. Thespring is charged during a portion of a breaker closing operation byutili z, ing closing movement of the blade contact to drive the lever ina spring-charging direction. At a subsequent intermediate point in theclosing stroke, the lever is released to permit the spring to dischargeand drive the lever in an opposite direction. Force-transmitting meansactuated by this latter movement of the lever is provided for drivingthe arcing contact away from the blade and into engagement with thefirst contact structure at a speed appreciably higher than closing speedof the blade.

For a better understanding of my invention, reference may be had to thefollowing description taken in connection with the accompanying drawing,wherein:

Fig. 1 is a side elevational view, partly in section, of an air circuitbreaker or switch embodying my invention 2,800,558 Patented July 23,1957 with the breaker being shown in the closed-circuit position.

Fig. 2 is a side elevational View of the circuit breaker of Fig. l withthe breaker being shown during an initial portion of a circuit-openingoperation. Certain of the parts shown in Fig. 1 have been omitted forsimplificatron.

Fig. 3 is fragmentary view showing a portion of the circuit breaker whenthe breaker is in its fully open position.

Fig. 3a is view taken along the line 3a-3a of Fig. 3 with only a portionof the circuit breaker of Fig. 3 being shown.

Fig. 4 is side elevational view, partly in section, showing the circuitbreaker during an intermediate portion of a circuit-closing operation.

Fig. 5 illustrates certain parts of the breaker during a portion of anopening operation.

Referring now to Fig. l, I have shown an air circuit breaker or switch10 of a type which is adapted both to interrupt load currents and todisconnect its associated circuit in the general manner of an air breakdisconnecting switch. In many respects the circuit breaker 10 is similarto the breaker shown and claimed in the aforementioned Harlow patent.

The breaker 10 comprises a pair of spaced-apart stationary terminals,indicated at 11 and 12, and a main current-carrying contact member 13which in its normal closed-circuit position shown in Fig. 1 is arrangedto electrically interconnect the terminals. The main contact member 13is formed as a contact blade which is pivotally mounted at its lower endon a stationary shaft 14. As can be best seen in Fig. 2, this shaft 14is suitably supported on conductive terminal brackets 15, and suitablespring washers 16 are provided to urge the blade 13 into frictionalengagement with the brackets so as to form a current-carrying hingejoint.

An operating link 18 is pivotally connected to the blade 13 and isdriven by suitable means (not shown) to cause pivotalcircuit-controlling movement of the blade to: ward and away from theupper terminal 11.

Electrically and mechanically connected to the upper terminal 11 isfixed contact structure including a stationary arcing contact 21 andmain current-carrying finger contacts 22 arranged to be engaged by theblade 13. These contacts are preferably of the same general type asdescribed in the aforementioned Harlow patent. Also fixedly mounted onthe upper terminal 11 is an arc-chute 24 which may be of any suitabletype but is preferably of the type shown in the aforementioned Harlowpatent. This arc chute 24 acts in a well-known manner to extinguish theare which is drawn adjacent the stationary arcing contact 21 during acircuit-opening operation.

For ooacting with this stationary arcing contact 21 to establish an are,there is provided a movable arcing contact 26. This arcing contact 26 issuitably electrically connected to the contact blade 13 and is pivotallymounted on the contact blade by means of a laterally-extending pivot pin28. A conventional torsion spring 30 encircles the pivot pin 28 andbiases the arcing contact 26 clockwise toward open position. When themain contact blade 13 is held in its closed position of Fig. l (by meansnot shown), the arcing contact 26 is prevented from rotating in aclockwise opening direction about its pivot 28 by a stop 31 fixed to theblade 13 and coacting with a slot 32 formed in the lower end of thearcing contact 26.

When the contact blade 13 is driven in a clockwise opening direction bya force applied to the operating link 18, the main contacts at 13, 22first part contact and move a predetermined distance toward fully openposition before parting of the arcing contacts 21 and 26. Since thearcing contact 26 is electrically connected to the main contact blade13, the circuit between the terminals will be opened at the arcingcontacts rather than at the main contacts. The position of the variousparts just prior to parting of the arcing contacts is shown in Fig. 2,where the main contacts 13 and 22 are shown separated and the arcingcontacts 21 and 26 are shown still in engagement.

To insure that the arcing contacts part at high speed so as to minimizethe duration of the arcing interval, the movable arcing contact 26 isinitially latched in closed position and movement of the blade 13 isutilized for charging the torsion spring 30. When the blade 13 reaches apredetermined open position, somewhat beyond that of Fig. 2, it releasesthe latch and permits the spring 30 to drive the arcing contact 26 athigh speed toward open position. 7

The above-mentioned latch is preferably in the form of a toggle 33, 34that is arranged to be overset, as shown in Figs. 1 and 2, andresiliently held in this position by means of a suitable overcenterspring 35. The upper end of the toggle link 34 is provided with a pin 36guided for limited vertical reciprocation in a slot 36a formed in themovable arcing contact 26. The pin 36 also carries a roller 37 laterallyoffset so as to be in alignment with a fixed catch 38 secured to thelower part of the arc chute along an edge thereof. The lower link 33 isconnected to a guide link 39 that is pivotally connected at 40 to thearcing contact and is biased by the spring 41 in a counterclockwisedirection so as normally to hold the latching toggle 33, 34 as a unit inits upper latching position.

As shown in Figs. 1 and 2, the latching toggle is controlled by means ofa tripping rod 42 secured to the blade 13 at its right hand end andcarrying a laterally ofiset extension 43 at its other end. The trippingrod 42 clears the toggle but the offset extension 43 is arranged so asto be substantially in alignment with the knee or central pivot 45 ofthe toggle. The toggle is held in the overset position shown in Figs. 1and 2 by the spring 35 and an extension formed on the lower toggle link33 to engage the upper toggle link 34. Accordingly, when the knee of thetoggle is moved suificiently overcenter by the action of the extension43, as will soon be described, the spring 35 causes collapse of thetoggle so that the roller 37 moves downward in the slot 36a sufficientlyto clear the catch 38.

Thus it will be apparent that when the blade 13 is moved in a clockwiseopening direction from the position of Fig. 1 to the position of Fig. 2,the toggle latch roller 37 will encounter the catch 38 and temporarilyrestrain the arcing contact 26 in engagement with the stationary arcingcontact 21. The overset toggle 34, 35 will maintain the movable arcingcontact 26 in this closed position until the moving blade 13 has driventhe extension 43 into engagement with the knee 45 of the latchingtoggle. Thereafter the action of the extension 43 causes the toggle tocollapse and permits the overcenter spring 35 to drive the roller 37downwardly out of latching relationship with the catch 38. This releasesthe arcing contact 26 and permits it to be snapped clockwise away fromthe fixed arcing contact 21 by the action of the torsion spring 38,which had been tensioned by prior opening movement of the contact blade13. This snap action of the arcing contact quickly draws an arc acrossthe lower end of the chute and permits the arc to be rapidlyextinguished within the chute in a well-known manner. As the openingmotion of contact blade 13 continues, the spring 41 of the toggle resetsthe toggle into its overset condition of Figs.

1 and 2. In the fully open position the contact blade 13 is essentiallyhorizontally disposed and rests against a suitable stop 47 which isprovided therefor.

If a relatively low speed mechanism is to be used for actuating thecontact blade 13, then the arcing contact 26 should be actuated towardclosed position, as well astoward open position, at a considerablyhigher speed than that of the blade. Otherwise, arcingfor an undesirablylong interval will occur as the contacts approach closed position at theend of a closing stroke.

For producing such high speed closing of arcing contact 26, I haveprovided a stored-energy type of closing mechanism generally indicatedat 50. As may be best seen in Figs. 3 and 3a, this mechanism 50comprises a compression spring 51 which is supported at its lower end bymeans of an adjustable nut 53 carried at the threaded lower end of amounting rod 54. The mounting rod 54 is pivotally suspended at its upperend by means of a pivot pin 55 supported on a stationary bracket 56.This bracket 56 projects from the lower terminal of the breaker and islocated adjacent the contact blade 13. Operatively coupled to the spring51 is a lever or bell crank 58, which is mounted for pivotal motionabout a stationary axis provided by a pivot pin 60. The pivot pin 60 issuitably supported on stationary bracket structure 62 which alsoprojects from the lower terminal adjacent the contact blade 13. As shownin Fig. 3a, the lower end of the lever 58 is formed as a clevis whichembraces and is pivotally connected to an annular thrust member 63,against which the upper end of the compression spring 51 bears. Thisthrust member 63 is mounted for sliding movement along the mounting rod54. Thus, it will be apparent that the compression spring 51, as seen inFig. 3, normally urges the lever 58 in a clockwise direction about itspivot 60 and into engagement with a suitable stop 65.

For reasons which will soon appear, the upper arm of the lever 58 is ofan articulated construction and includes a pawl 67 which is pivotallyjoined to the main body of the arm by a pivot pin 68. This pivot pin 68is carried by a tongue-like projection 69 which is freely received in asuitable clevis formed at the lower end of the pawl 67. The lower clevisend of the pawl 67 has surfaces 71 which bear against correspondingabutting shoulders provided on the lever 58. An extension spring 72normally maintains these surfaces 71 in engagement with said abuttingshoulders so as to preclude counterclockwise rotation of the pawl aboutits pivot 69 from the position shown in Fig. 3.

This stored-energy closing mechanism 50 is normally in a dischargedcondition, as can be seen in Figs. 1 and 3. However, as will soonappear, when the blade 13 is moved counterclockwise from the position ofFig. 3 to close the breaker, closing movement of the blade 13 becomeseffective to charge the mechanism 50. At a subsequent point in theclosing stroke, when the mechanism 50 is charged, it is released andpermitted to discharge at high speed. This discharging action isutilized to drive the arcing contact 26 about its pivot 28 and intoclosed position at a speed appreciably higher than the normal closingspeed of the blade 13.

For charging the mechanism 50 during the closing stroke, the blade 13 isprovided with a downwardly projecting lug or abutment 75, which issecured to the blade. When the blade 13 is rotated in a counterclockwiseclosing direction from the solid line position of Fig. 3, this ing 75,after a predetermined portion of the closing stroke, moves intoengagement with rear edge of the pawl 67. The position of the parts atthis instant is illustrated by dot-dash lines in Fig. 3.

' After this engagement occurs, continued closing movement of the blade13 causes the lug 75 to rotate the lever 58 in a counterclockwisedirection about its pivot 60, .thereby progressively compressing thespring 51. During this interval, the pawl 67 simply acts as a rigidextension of the upper arm of the lever 58 due to the abuttingrelationship between the surfaces at 71. Coincident with thisspring-charging operation, the forward or driving surface of the lug 75slides upwardly along the rear edge of the pawl 67, this relativemovement resulting from the fact that the pivot for the blade 13 islaterally offset from the pivot for the lever 58. Eventually, thisrelative movement will progress to a point at jectional reboundmovement.

which the driving surface of lug 75 moves out of engagement with thepawl 67, at which time the pawl 67 and its lever 58 will be released forreverse movement under the influence of the then-charged spring 51. Theposition of the parts just prior to such release is illustrated in solidlines in Fig. 4.

When release does occur, the spring 51 quickly discharges to drive thelever 58 clockwise at high speed about its pivot 60. As a result of suchclockwise movement, the pawl 67 is driven into engagement with aforcetransmitting pin 77 secured to the lower end of the arcing contact26. Thereafter, the discharging spring 51, acting through the pawl, ordriving member 67 and the pin, or driven member, 77, drives the arcingcontact 26 counterclockwise about its pivot 28 and into closed positionwith respect to the stationary arcing contact 21. The position of theparts after the spring 51 has discharged in this manner is illustratedby the dot-dash lines of Fig. 4.

From the solid line position of Fig. 4 it can be seen that at theinstant the pawl 67 is released, the forcetransmitting pin 77 is spacedan appreciable distance from the pawl. This space, which might be termedan impacting distance, allows the pawl, when driven by discharge of thespring 51, to impart to the pin 77 a sharp hammer-blow which materiallycontributes to driving the arcing contact 26 into its closed position athigh speed.

Closing movement of the arcing contact 26 is opposed by the contactopening spring 30, but the closing spring 51 is of such a size that ithas ample power to overcome this opposition. The opposing force of theopening spring 30 does however tend to produce rebound of the arcingcontact 26, and if such rebound were permitted, arcing could beundesirably reinitiated between the arcing contacts. To preclude suchrebound, the pawl, or driving member 67 is provided with a cam surface80 which rides underneath the pin, or driven member 77 shortly after thearcing contacts engage and, in such position, restrains the movablearcing contact 26 from significant reverse or rebound movement. Thedotted lines of Fig. 4 show the cam surface 80 disposed in such areboundpreventing position.

As closing movement of the main blade 13 continues in a counterclockwisedirection from the dotted line position of Fig. 4, theforce-transmitting pin 77 simply slides along the cam surface 80. As aresult, the cam surface '80 continues to restrain the arcing contact 26from ob- The cam surface 80 and later the slot 32 assure that the arcingcontacts remain in engagement until the slow-moving main contact blade 3finally engages its coacting stationary contact 22. Thereafter, theparts ultimately move into the normal closed-circuit position of Fig. l.

An'advantageous feature of my above-described circuit breaker is thatthe supplementary closing mechanism 50 does not interfere with theopening movement of the arcing contact 26. The pawl 67 is actually inthe path of the arcing contact 26 during its opening movement, but sincethe pawl is free to collapse in a clockwise direction about its pivot68, the arcing contact simply brushes it aside in a clockwise directionwithout significant interference therefrom. When the contact blade 13has sufiiciently opened, the return spring 72 is free to reset the pawl67 to its position shown in Fig. 3. The manner in which the pawl 67 isbrushed aside to allow for opening operation is shown in Fig. where thepawl has been pivoted clockwise about its fulcrum 68.

Another factor which contributes to the ability of the arcing contact 26to open without interference from the closing mechanism 50 is that theforce-transmitting pin 77 is moved out of force-transmittingrelationship with respect to the cam surface 80 during final closingmovement of the contact blade 13. This can be seen in Fig. 1. .As aresult of this disengagement, the cam surface 80 cannot restrain thearcing contact 26 from opening movement during a subsequent openingoperation.

While I have shown and described a particular embodiment of myinvention, it will be obvious to those skilled in the art that variouschanges and modifications may be made without departing from myinvention in its broader aspects and I, therefore, intend in theappended claims to cover all such changes and modifications as fallwithin the true spirit and scope of my invention.

What I claim as new and desire to secure by Letters Patent of the UnitedStates is:

1. An electric circuit breaker comprising first contact structure, amain contact blade movable into and out of engagement with said firstcontact structure, an arcing contact pivotally mounted on said blade andmovable with respect to both said blade and said first contactstructure, a chargeable spring supported independently of said blade forcontrolling closing movement of said arcing contact, means controlled byclosing movement of said blade for charging said spring during a portionof a closing stroke, means operable at a subsequent point in saidclosing stroke for releasing said spring to permit discharge thereof,andmeans actuated by discharge of said spring for driving said arcingcontact away from said blade and into engagement with said first contactat an elfective speed appreciably higher than the closing speed of saidblade.

2. An electric circuit breaker comprising first contact structure, amain contact blade movable into'and out of engagement with said firstcontact structure, an arcing contact pivotally mounted on said blade andmovable with respect to both said blade and said first contactstructure, a chargeable spring for controlling closing movement of saidarcing contact, means controlled by closing movement of said blade forapplying a springcharging force to one end of said spring during aportion of a blade-closing stroke, and means operable at a subsequentpoint in said closing stroke for releasing said spring at said one endthereof to permit said spring to discharge, and force-transmitting meansactuated by discharge of said spring for driving said arcing contactabout its pivot on the blade and into engagement with said first contactstructure at an effective speed appreciably higher than the closingspeed of said blade.

3. An electric circuit breaker comprising first contact structure, apivotally-mounted main contact blade coacting with said first contactstructure and movable with respect thereto, an arcing contact pivotallymounted on said blade and movable with respect to both said blade andsaid first contact structure, a chargeable spring for controllingclosing movement of said arcing contact, a lever operatively coupled tosaid spring and mounted for pivotal motion, means controlled by closingmovement of said contact blade for moving said lever in a direction tocharge said spring during a portion of a closing stroke, and means forreleasing said spring at a subsequent intermediate point in said closingstroke to permit said spring to discharge and move said lever in adirection opposite to the spring-charging direction, and forcetransmitting means actuated by movement of said lever in said oppositedirection for driving said arcing contact away from said blade and intoengagement with said first contact structure.

4. The circuit breaker of claim 3 in which lost motion is providedbetween said lever and said arcing contact for enabling said spring toimpart a hammer blow to the arcing contact after release of said lever.

5. An electric circuit breaker comprising first contact structure, apivotally-mounted main contact blade movable into and out of engagementwith said first contact structure, an arcing contact pivotally mountedon said blade and movable with respect to both said blade and said firstcontact structure, a chargeable spring for controlling closing movementof said arcing contact, a lever operatively coupled to said spring andmounted for pivotal motion, an abutment movable with said contact bladeand tion to said lever during a portion of a blade-closing stroke,

said driving surface being movable out of restraining relationship withsaid lever at a subsequent point in said closing stroke to permit saidspring to discharge and move said lever in a direction opposite to thatof said springcharging motion, and force-transmittingmeans actuated bymovement of said lever in said opposite direction for driving saidarcing contact away from said blade and into engagement with said firstcontact.

6. The circuit breaker of claim in which the pivot axis for said contactblade is laterally spaced from the pivot axis for said lever so as toenable the driving surface of said abutment to move out of restrainingrelationship with said. lever at said subsequent point in the closingstroke. T

7. An electric circuit breaker comprising first contact structure, amain contact blade movable into and out of engagement with said firstcontact structure, an arcing contact pivotally mounted on said blade andmovable with respect to both said blade and first contact structure, achargeable spring for controlling closing movement of said arcingcontact, means controlled by closing move- 'ment of said blade forcharging said spring during a portion of a closing stroke, meansoperable at a subsequent point in said closing stroke for releasing saidspring to permit discharge thereof, and means actuated by discharge ofsaid spring for driving said arcing contact away from said blade andinto engagement with said first contact at an eifective speedappreciably higher than the closing speed of said blade, saidlast-mentioned means comprising a lever having a portion which isencountered by said arcing contact during a subsequent openingoperation, and means for allowing said portion of the lever to moverelative to the remainder of the lever When encountered by said arcingcontact during an opening operation whereby to prevent said lever frominterfering with said opening operation.

8. An electric circuit breaker comprising first contact structure, amain contact blade movable into and out of engagement with said firstcontact structure, an arcing contact pivotally mounted on said blade andmovable with respect to both said blade and said first contactstructure, a chargeable spring for controlling closing movement of saidarcing contact, means controlled by closing movement of said blade forcharging said spring during a portion of a closing stroke, meansoperable at a subsequent point in said closing stroke for releasing saidspring to permit discharge thereof, and means actuated by discharge ofsaid spring for driving said arcing contact away from said blade andinto engagement with said first contact at an effective speedappreciably higher than the closing speed of said blade, said drivingmeans comprising a driving member and a driven member, the drivingmember being provided with a cam surface which moves intorebound-preventing engagement with the driven member shortly after themovable contact engages said first contact structure.

9. In an electric circuit breaker of the type comprising first contactstructure, a pivotally-mounted main contact blade movable into and outof engagement with said first control structure, an arcing contactpivotally mounted on said blade and movable with respect to both saidblade and said first contact structure, and means including a firstspring for moving said arcing contact away from said first contactstructure and toward said blade after a predetermined opening movementof said blade; the combination of a second spring for controllingclosing movement of said arcing contact, means controlled by closingmovement of said blade for charging said second spring during a portionof a bladefclosing stroke, and means operable at a subsequentintermediate point in said closing stroke for releasing said secondspring to permit discharge thereof, and means actuated by discharge ofsaid second spring and opposed by said first spring for driving saidarcing contact toward said first contact structure and away from saidblade against the bias of said first spring.

10. The circuit breaker of claim 9 in which said means for driving thearcing contact toward said first contact structure comprises a leverhaving a portion which is encountered by said arcing contact during asubsequent opening operation, and means for allowing said portion of thelever to move relative to the remainder of the lever when encountered bysaid arcing contact during an opening operation whereby to prevent saidlever from i11terfering with said opening operation.

11. The circuit breaker of claim 9 in which said means for driving thearcing contact toward said first contact structure comprises a drivenmember and a driving member, the driving member being provided with acam surface which moves into rebound-preventing engagement with thedriven member shortly after the movable arcing contact engages saidfirst contact structure.

12. The circuit breaker of claim 11 in which final closing movement ofsaid blade moves said arcing contact out of restrained relationship withrespect to said cam surface whereby to permit initial opening movementof the contact to take place free from restraint by said cam surface.

13. The circuit breaker of claim 9 in which said means for driving thearcing contact toward said first contact structure comprises a drivingmember and a driven member which are moved out of force transmittingrelationship with respect to each other by final closing movement ofsaid blade.

14. In an electric circuit breaker of the type comprising first contactstructure, a pivotally mounted main contact blade movable into and outof engagement with said first contact structure, an arcing contactpivotally mounted on said blade and movable with respect to both saidblade and said first contact structure, and means including a firstspring for moving said arcing contact away from said first contactstructure and toward said blade after a predetermined opening movementof said blade; the combination of a second spring for controllingclosing movement of said arcing contact, a lever operatively coupled otsaid spring and mounted for pivotal motion, means controlled by closingmovement of said blade contact for moving said lever in a direction tocharge said spring during a portion of a blade-closing stroke, and meansfor releasing said lever at a subsequent intermediate point in saidclosing stroke to permit said spring to discharge and move said lever inan opposite direction, and force-transmitting means actuated by movementof said lever in said opposite direction and opposed by said firstspring for driving said arcing contact toward said first contactstructure and away from said blade against the bias of said firstspring.

References Cited in the file of this patent UNITED STATES PATENTS1,935,428 Atwood Nov. 14, 1933 2,399,485 Harlow et al. Apr. 30, 19462,697,153 Owens et al Dec. 14, 1954

